Wound dressings are known in which an adhesive layer is backed by a film of polyurethane or other suitable polymeric film and in which the bodyside surface (the wound-contacting surface) is covered by two or more removable release sheets. Each release sheet covers only a portion of the bodyside surface of the adhesive layer, with each sheet usually being butterfly folded to present diverging flaps extending along the line of meeting. Such flaps are used to grip the release sheets and peel them away from each other to expose the adhesive layer, and it has also been found convenient to utilize such flaps, after they have been partially removed, as preliminary gripping means for orienting the dressing and applying it to a wound site. One disadvantage of such a construction lies in the fact that the release sheets may not completely cover the adhesive surface of the dressing along the line of meeting, thereby creating the possibility that a narrower surface portion of the adhesive may be subject to deterioration and possible contamination during storage and application.
Such problems may be reduced by reversely-folding only one of the two release sheets as disclosed, for example, in U.S. Pat. No. 4,598,004. The advantages of such a construction are offset, however, by the fact that the release covering is then of triple thickness along one side of the fold line, usually creating a noticable step in the adhesive and backing layers overlying the fold. That disadvantage is compounded if the adhesive layer is a soft, pliant, fluid-absorbing, hydrocolloid-containing composition of a type now commonly used for wound dressings because, in such a case, the adhesive layer may become significantly deformed prior to application of the dressing and the effectiveness of the dressing in protecting a wound and absorbing exudate may be compromised. While the step effect might be reduced by omitting the reverse fold from one of the release sheets, so that only a double thickness of release sheet material exists along that portion overlapped by the flap of the other release sheet, the benefits of providing double flaps for ease of application, and to facilitate removal of both sheets, are then lost or at least diminished.
Other references illustrating the state of the art are U.S. Pat. Nos. 5,000,172, 5,336,162, 5,106,629, 5,423,737, 4,614,183 and 2,969,057.
One aspect of this invention lies in providing a wound dressing, preferably a dressing in which the adhesive layer is of a fluid-absorbing hydrocolloid-containing adhesive composition, utilizing a delivery system that overcomes the aforementioned defects and disadvantages of the prior art. In a dressing embodying this invention, the release sheet means takes the form of a primary release sheet and a release strip that cover the entire bodyside surface of the adhesive layer, with at least a portion of the release strip being interposed between the primary release sheet and a part of the bodyside surface along an outer edge portion of the dressing. Both the primary release sheet and the release strip are formed of flexible stretch-resistant sheet material and have their opposing surfaces unsecured to each other or at least readily separable from each other. Of particular importance in a preferred embodiment is the fact that both the primary release sheet and the release strip have tab portions that are superposed and project outwardly beyond the outer limits of the adhesive layer to assist a user in initiating a peeling back of the primary sheet and strip and to facilitate application of the dressing to a wound site.
The backside of the adhesive layer is covered by an elastomeric backing film. Ease of application of the dressing is further enhanced by reason of the adhesive layer and backing film being formed of translucent material and the release strip and primary release sheet (visible through the backed adhesive layer) being of contrasting colors or tones. Ideally, the primary release sheet is of a neutral color (white or whitish) and the release strip is of a darker contrasting color. In one embodiment, the tab portion of the release strip is smaller than the tab portion of the primary release sheet directly below and, because of the color or tonal contrast, a user may readily distinguish the two tab portions and urge them apart in commencing the steps of preparing the dressing for application. In a second embodiment, it is the tab portion of the release strip that is the larger of the two and, again, separation of the release sheet and release strip is facilitated by the color or tonal contrast.
While the planar wound dressing may assume different configurations, in a preferred embodiment the dressing is generally rectangular in outline with straight side edges and rounded corners, and the release strip extends along one of the side edges of the dressing. In such a construction, the superposed tab portions are preferably located at one of the rounded corners of the dressing and project outwardly therefrom.
An additional advantage of the dressing as so described is that in production it may be cut into its final shape in a single die-cutting operation, thereby eliminating many of the costs associated with the production of dressings requiring multiple die-cutting steps. To facilitate single-step cutting operations, it has been found desirable to form the release strip with parallel longitudinal side edges and with the tab portion of the strip (and also the underlying tab portion of the primary release sheet) extending endwise from the strip. Edges of the two tab portions nearest the inboard longitudinal edge of the release strip are offset in an outward direction from that inboard edge to assure completeness of cutting during the one-step cutting operation.